[VectorCombine] foldSelectShuffle - remove extra adds of old shuffles to worklist

We already push the old shuffles to the worklist as part of the replaceValue calls, so we shouldn't need to add them to the deferred list as well - my guess is this was to ensure that the instructions got erased first to help cleanup unused instructions, but eraseInstruction should handle this now.

Author: RKSimon

llvm/lib/Transforms/Vectorize/VectorCombine.cpp

@@ -3036,8 +3036,6 @@ bool VectorCombine::foldSelectShuffle(Instruction &I, bool FromReduction) {
   Worklist.pushValue(NSV0B);
   Worklist.pushValue(NSV1A);
   Worklist.pushValue(NSV1B);
-  for (auto *S : Shuffles)
-    Worklist.add(S);
   return true;
 }